1. Field of the Invention
This invention relates to a color picture image forming apparatus in which an optically read manuscript picture image data is decomposed into plural types of color signals and a manuscript picture image is reproduced on a recording medium based on the decomposed manuscript picture image data, and more particularly to apparatus for reproducing a color picture image while enlarging or reducing the size thereof.
2. Description of the Prior Art
As a color image forming apparatus, an electrophotographic color copying device has been known in which a picture image is formed by forming an electrostatic latent image on a drum. In such an electrophotographic color copying apparatus, filters of three primary colors (cyan, magenta, yellow) are used to sequentially form electrostatic latent images of red, green and blue colors on the drum, the latent images are developed with tones of three colors and the developed image are sequentially transfer printed onto a printing paper thus reproducing a color picture image.
In such a copying apparatus, when the picture image is enlarged or reduced, a desired magnification or reduction is obtained by moving a lens system to a predetermined position corresponding to degree of the magnification or reduction. In this apparatus, there are such problems that it takes a certain time to move the lens system and that the magnification or reduction degree is fixed. Moreover, the prior art apparatus has a complicated construction and large dimensions.
In recent years, a thermal transfer printing type color copying apparatus has been proposed in which thermal transfer printing type ink ribbons of a plurality of colors are used to obtain color copies. Briefly stated, in such a copying apparatus, a manuscript is scanned with an optical system to read out the picture image information of the manuscript as color light signals, the read out picture image information are converted into color information corresponding to respective inks of the thermal transfer printing ink ribbons, and the color information of respective inks are temporarily stored in memory means. The color information thus stored is sequentially read out and inks corresponding to the thermal transfer printing ink ribbons corresponding to the read out color information are used for thermally transfer printing the inks onto the copying paper by using a heat sensitive head, thereby sequentially transfer printing respective colors onto the paper to obtain a color copy.
However, a copying machine of this type with an image enlarging or reducing function has not yet been realized. Thus, the copying machine of this type with adequate enlarging or reducing function has been desired.